The safety measures at nuclear power plants derive directly from our top priority: "To ensure that, under all conceivable circumstances, the community will be protected from hazardous radioactive substances."
To that end, we have thoroughly incorporated the "defense in depth concept," which is the foundation of genuine safety. Thus, safety measures are built in at every stage of the process.
Defense in Depth
1. Measures to prevent unexpected events
- All designs provide margins of safety capable of withstanding even natural disasters.
- Strict quality control at every stage, from design to construction to operation.
- In addition to the elaborate regular inspections that take place every year, interlock and fail-safe systems are incorporated at every turn to prevent erroneous operations or actions.
2. Measures to prevent the escalation of unexpected events
- Detection devices to detect abnormalities immediately
- Equipment that automatically and safely shuts the reactor down
3. In the extremely unlikely event of an accident
[to prevent release of radioactive substances]
- Emergency Core Cooling System (ECCS)
- Airtight structure of the primary containment vessel and the reactor building
Anti-Earthquake Measures
Designed for the Largest Conceivable Earthquake
Before constructing a nuclear power plant, the site is carefully studied for previous earthquake records and geological features. This study establishes that there is no active fault under the site. Then, the building, the equipment, the piping, and other equipment are all designed to withstand the strongest possible earthquake in the area.
Hard-to-Shake Structure
Reactor buildings are built directly on solid bedrock after all soil has been removed. Furthermore, the reinforced concrete walls are far thicker than those used in other buildings. The building itself is a strong dice-like structure. Therefore, in the event of an earthquake, reactor buildings shake far less than an ordinary building.
Automatic Shutdown
Seismic detecting devices in the reactor building are designed to automatically shut the reactor down if they sense an earthquake of level 5 or greater.
Operation / Skills Training
In addition to the many safety measures related to plant and equipment, the operators and maintenance personnel receive periodic strict and thorough training on the job and in the training center. Every effort is made to ensure safe operation.
BWR Operation Training Center
Skills Training Center
Five Barriers Enclosing Radioactive Substances
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